In the ever-present chase for fuel mileage, the rings were left too loose, and they burn oil. The replacement engines will get worse fuel mileage. We had many complaints at the dealership where I worked, as the advisors didn't make this clear enough up front.
The lawsuit brought the warranty up to 100k miles, I don't know if there was a time limit on that. Early warranty repair was to replace rings, but then they changed to using brand-new shortblocks, either to reduce labor cost, or problems, or both. Even still, it's no small job, and we saw more than a few comebacks due to oil leaking from the timing cover or cam carriers.
Running 5w30 (synthetic, of course) helps.
You can use a used engine from newer model with a few small changes. A friend of mine bought a 2011 Forester with a blown engine, not knowing it was an FB. And he ended up getting an engine from a 2015 or so and swapped it in. Sorry, I don't remember all the details, but it wasn't anything major. There must be some documentation on it.